This invention relates to the field of display systems, more particularly to processing image data for display systems.
Advances in image display technology have improved the ability of image displays to recreate scenes with great accuracy. Many applications, however, must deal with human perception as they strive to produce images that are both accurate and visually pleasing. This is especially true in the field of digital image processing. While digital techniques provide very high resolution and color fidelity, digitally processing image data can lead to perceptible artifacts in the created images. What is needed is a system and method of improving perceived image quality while minimizing the degradation of image fidelity.
Objects and advantages will be obvious, and will in part appear hereinafter and will be accomplished by the present invention which provides a method and system for intensity level expansion. One embodiment of the claimed invention provides a method of processing image data that selectively scales portions of the image data based on the proportion of image pixels that meet predetermined intensity thresholds.
The method comprises the steps of: providing a first intensity threshold value, a frame intensity threshold value, and an intensity knee; receiving a series of frames of image data, the image data comprising at least one intensity data word for each pixel of each frame; comparing the intensity data words to the first threshold and accumulating a first number representative of the number of intensity data words in a frame that meet an intensity criteria relative to the first threshold; and scaling a portion of said intensity data words when said first accumulated number exceeds said frame intensity threshold value.
An optional additional step increments a frame accumulator value each time the first accumulated number exceeds the frame intensity threshold value, the step of scaling comprising scaling by a factor determined by the frame accumulator value. Another optional additional step decrements the frame accumulator value each time the first accumulated number does not exceed the frame intensity threshold value.
According to another embodiment, another method of processing image data is provided. The method comprising the steps of: providing a first intensity threshold value, a second intensity threshold value, a frame intensity threshold value, and an intensity knee; receiving a series of frames of image data, the image data comprising at least one intensity data word for each pixel of each frame; comparing the intensity data words to the first threshold and accumulating a first number representative of the number of intensity data words in a frame that meet an intensity criteria relative to the first threshold; comparing the intensity data words to the first threshold and accumulating a second number representative of the number of intensity data words in a frame that meet an intensity criteria relative to the second threshold; and scaling a portion of the intensity data words when the first accumulated number exceeds the first frame intensity threshold value and the second accumulated number exceeds the second frame intensity threshold value.
An optional additional step increments a frame accumulator value each frame the first accumulated number exceeds the first frame intensity threshold value and the second accumulated number exceeds the second frame intensity threshold value, the step of scaling comprising scaling the portion by a factor determined by the frame accumulator value.
Another optional additional step decrements the frame accumulator value each frame the first accumulated number does not exceed the first frame intensity threshold value or the second accumulated number does not exceed the second frame intensity threshold value.
According to another embodiment of the disclosed invention, a display system is provided. The display system comprising: a controller for selectively scaling input image data and a display device for displaying said selectively scaled image data. The controller comprising an input to receive the input image signal comprised of intensity data for a plurality of pixels and a level expansion circuit operable to monitor the intensity data an selectively scale portions of the intensity data based on the intensity data.
According to another embodiment, the level expansion circuit further comprises at least one histogram comparator operable to receive input data and an intensity threshold. The histogram comparator further operable to accumulate a number representing the number of pixels in the input image signal that meet an intensity criteria relative to the intensity threshold.
According to another embodiment, the level expansion circuit further comprises a field accumulator operable to receive a signal from at least one histogram comparator indicating that a sufficient number of pixels in the input image signal meet the intensity criteria. The field accumulator accumulates a value determined by the number of frames of the input image signal in which a sufficient number of pixels meet the intensity criteria.
According to yet another embodiment, the level expansion circuit further comprises a level expander operable to selectively scale portions of the intensity data based on the accumulated value from the field accumulator.